1. Field of the Invention
The invention relates to a loudspeaker system, more particularly to a loudspeaker system with stackable loudspeaker units for achieving a surround sound effect.
2. Description of the Related Art
A loudspeaker is used for an audio system and includes a loudspeaker enclosure and a loudspeaker mechanism. When sound is generated by the loudspeaker mechanism, positive and negative sound pressures are produced in front of and behind the loudspeaker mechanism. In the loudspeaker enclosure, the negative sound pressure behind the loudspeaker mechanism creates echo resonance, which can interfere with the sound pressure produced in front of the loudspeaker mechanism so as to affect adversely the quality of sound output.
Referring to FIGS. 1 and 2, a conventional loudspeaker 10 includes a loudspeaker enclosure and tweeter, midrange and woofer loudspeaker mechanisms 141, 142, 143 mounted on the loudspeaker enclosure. The loudspeaker enclosure includes a closed box 15, an inner baffle wall 12 disposed in the box 15, a ducting member 13 disposed in a bottom portion of the box 15, and a plurality of port openings 11 formed in a front side of the box 15. The baffle wall 12 encloses and isolates the tweeter and midrange loudspeaker mechanisms 141, 142 from the woofer loudspeaker mechanism 143. The ducting member 13 includes a horizontal plate 131 and a vertical plate 132 connected to the horizontal plate 131. As such, the sound pressures behind the tweeter and midrange loudspeaker mechanisms 141, 142 can be radiated directly through the upper port opening 11, while the sound pressure behind the woofer loudspeaker mechanism 143 can be radiated through the lower port opening 11 via the ducting member 13 to avoid echo resonance.
The following are some of the drawbacks of the conventional loudspeaker 10:
1. The loudspeaker 10 includes the tweeter, midrange and woofer loudspeaker mechanisms 141, 142, 143, and the sound is radiated in the same direction. Thus, the loudspeaker 10 cannot provide a surround sound effect.
2.The radiating coverage of the port openings 11 is relatively small, and sound is hardly radiated to the whole area of an audiovisual room.
3.Since an inner space of the box 15 is limited, only the sound pressure due to the woofer loudspeaker mechanism 143 is designed to pass through the ducting member 13. As such, the high frequency and midrange frequency response of the loudspeaker 10 is poorer as compared to the lower frequency response of the same.
Therefore, the main object of the present invention is to provide a loudspeaker system with stackable loudspeaker units that can achieve a surround sound effect.
According to this invention, a loudspeaker system includes at least two loudspeaker units. Each of the loudspeaker units includes a loudspeaker enclosure and at least one loudspeaker mechanism mounted on the loudspeaker enclosure. The loudspeaker enclosure includes an outer cabinet body and an inner baffle frame.
The cabinet body has an open front side, a closed rear side, opposed lateral walls, and opposed top and bottom walls that extend in a first horizontal direction between the front and rear sides.
The baffle frame is disposed in the cabinet body, and has parallel left and right walls that extend in a vertical direction between the top and bottom walls and that form a sound space therebetween. The left and right walls further form first clearances with the lateral walls of the cabinet body respectively, and have a front portion that is proximate to the front side of the cabinet body and that has the loudspeaker mechanism mounted thereon. The front portion of the left and right walls cooperates with the lateral walls to form a pair of acoustic port openings at front ends of the first clearances. The left and right walls further have a rear portion that forms a second clearance with the rear side of the cabinet body. The second clearance is communicated with and extends between rear ends of the first clearances in a second horizontal direction transverse to the first horizontal direction. The baffle frame further has a ducting member at the rear portion of the left and right walls. The ducting member forms an acoustic path that communicates the sound space and the second clearance such that sound pressure behind the loudspeaker mechanism can be radiated through the acoustic port openings via the sound space, the acoustic path, the second clearance and the first clearances.